This application relates to uronic acid nucleosides. Additionally, this application relates to methods for preparing such compounds, including the preparation of a class of general intermediates from which, by process steps described herein, a variety of uronic acid nucleosides can be readily produced. Novel uronic acid nucleosides are described.
In copending application Ser. No. 119,019, filed Feb. 25, 1971, now U.S. Pat. No. 3,809,689, and assigned to the assignee of the present invention, there is disclosed, inter alia, a class of nucleosides having the general formulae: ##SPC3##
Where B is selected from various pyrimidine or purine bases identified therein.
The designations Ic and Id represent the .beta.-D-allo and the .alpha.-L-talo epimers in which the 5'-amino groups have the opposite configurations. These designations are as given in the aforementioned copending application and will be followed in this application to enable easier review, comparison and understanding of these two related applications.
On pages 20-26 of the specification of the aforementioned copending application there is described, in detail, a process for preparing the compounds of formulae Ic and Id. A schematic flow chart of that process is given on pages 20-21 thereof. This process, though quite capable of being used, as indicated, to produce the compounds of formulae Ic and Id, is not totally satisfactory since the process requires careful tailoring of the starting compound (Z) in view of the particular nucleoside desired, and because the strongly acidic conditions necessary to effect hydrolysis of the amide function to a carboxylic acid would result in almost complete hydrolysis of the intermediate nucleoside to the corresponding sugar when applied to purine derivatives. Since the process is limited by the exclusion of steps which include highly acidic conditions, it is correspondingly limited in the nucleosides which can be produced therewith. Accordingly, it would be desirable to have a more general process for producing the nucleosides of formulae Ic and Id, such process including the preparation of a class of general intermediates from which many nucleosides (having a structure represented by either formula Ic or Id) can be readily prepared in only a few steps.